<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>

    <style>

        body {
            margin: 0;
        }

        footer {
            width: 100%;
            height: 100px;
            background-color: cornflowerblue;
            display: flex;
        }

        .box {
            flex: 1;
            height: 100%;
            outline: 1px solid red;
            display: flex;
            /* 改变主轴的方向 */
            flex-direction: column;
            /* 主轴侧轴居中 */
            justify-content: center;
            align-items: center;
            display: flex;
        }


    </style>
</head>
<body>
    <footer>
        <div class="box">
            <div>1</div>
            <div>hello world</div>
        </div>
        <div class="box">
            <div>1</div>
            <div>hello world</div>
        </div>
        <div class="box">
            <div>1</div>
            <div>hello world</div>
        </div>
        <div class="box">
            <div>1</div>
            <div>hello world</div>
        </div>
        <div class="box">
            <div>1</div>
            <div>hello world</div>
        </div>
    </footer>
</body>
</html>